Eccentric Gem – AUTOMOBIL REVUE

No flat six cylinders! Large cylinder heads can be misleading. And behind them are common combustion chambers for each two cylinders.

There is an intimate relationship between the Ferrari and 12-cylinder engines. From the beginning to this day, lofty V12 engines have been the heart of the brand. They are for Ferrari what the numbers are for Chanel.
mer 5 is: a necessity, an identity mark that traces its roots to the origins of the brand. The cylinders in Maranello were not always arranged in the traditional V-shape. Ferrari has deviated several times from the original concept that came from Guacchino Colombo. In 1971, for example, the twelve cylinders in the 365 GT4 BB were arranged flat at Maranello. For over 20 years, up to the 1991 512 TR, Ferrari sedans were powered by a rear boxer. Then a few more years passed before that, in 1994, Ferrari engineers tried an even more unusual arrangement of the twelve: the diamond shape.

You will ask yourself what is meant by this, because the term diamond shape is not found in any textbook on engine construction. However, the revolutionary cylinder arrangement that Ferrari tested is arguably best described: two V6 engines stacked on top of each other, with the upper engine turned over so that the crankshaft was on top. Both V6 engines share a common cylinder head, and the engine has only six combustion chambers – one for each of the two cylinders. Looking at the six syringes (three per side) and the width of the engine, you’d think it was a flat six. We also almost fell in love with it and thought Ferrari had been stolen in Porsche country. But the alleged scoop was not, even the inscription “DiV6” on the cylinder head should have taught us better. This was the start of extensive research, aside from some old and obscure forum posts, there isn’t much on the internet about this drive, which turns everything upside down.

A stimulating environment for creativity

In the absence of reliable information, we look at the source: engineers Alessandro Marchetti and Roberto Roncaglia, who worked on the mysterious prototype under the direction of Ennio Ascari, told us more about the engine. The idea for the 4.6-liter twin-turbo V6 originated at Ferrari Engineering, an independent company under the Breeding Horse banner, which ran between 1988 and 1995. Logically, the engineers working there primarily worked for Ferrari. However, they have also worked for outside companies in a variety of fields. For example for the famous bike manufacturer Colnago, for NASa, Riva Motoscafi (motor boats) and Cagiva. “The atmosphere was very favorable for developing ideas like those for the DiV6 engine, because the way it worked was very purposeful,” says Alessandro Marchetti. The guys presented the progress of their work to Paolo Martinelli, who headed the Scuderia Ferrari engine division from 1994 to 2006. He was the man who heralded Maranello’s F1 glory years as its V10 engines won six constructors’ and five drivers’ titles (between 1999 and 2004). So Martinelli had to look over the shoulder of Ennio Ascari, the innovative brain behind DiV6. “Because the new Ferrari should always be faster than its predecessor, we started this project to reduce the longitudinal expansion of the engine and to gain more space under the hood,” says Roberto Roncaglia. So Ferrari Engineering worked on a workaround for the V12 F116B engine pulsing under the hood of the 456 GT.

But the engineers soon ran into obstacles. Catalytic converters were introduced in the mid-1990s, and since the DiV6 itself was already very tall, this caused problems. The hood must be raised to accommodate the catalytic converters – to the middle of the windshield. The project was canceled before the engineers had access to the exhaust or intake manifolds, as the F135A had much bigger problems to deal with. “The massively enlarged shape of the combustion chamber means that the spark plugs cannot be optimally positioned to ignite the fuel-air mixture,” says Roberto Roncaglia. “We also found that the thrust exerted by each cylinder was asymmetrical.” So Ferrari should have at least resorted to dual ignition, a solution that Alfa Romeo has also used in its Twinspark models to solve the problem.

Fatal problem with seal

In addition to uneven combustion, there was a larger problem that nipped the F135 DiV6 development in the bud: blowing. This term means insufficient sealing of the pistons, with combustion residues flowing through the piston and penetrating the crankcase. In a conventional engine, this is prevented by piston rings. But the DiV6 was not a conventional engine, the swollen shape of the combustion chamber required a triangular piston shape. The o-rings had to be put down, below the pumping pin, so it looks pretty deep. Leftover unburned fuel and exhaust gases can travel down the connecting rod (or up if you’re talking about an upper V6) and end up in the crankcase. “This problem prevented further development because the engine could not start due to high pressure,” explains Alessandro Marchetti, who still remembers the first attempts to revive the DiV6 engine on the test bench. “New parts are designed with seals on the piston pin to reduce blowout,” Marchetti says. Unfortunately, it was never used.

When weighing the pros and cons, the problems and complexity of the DiV6 far outweighed the benefits of its compactness. Plus, at least in the early stages of development, it was no more powerful than the Ferrari 456 V12 that served as a reference. The twin-turbo V6 was 415 horsepower, while the F116B was rated at 442 horsepower. However, there was one important difference to the DiV6 credit: Specific power – a value of paramount importance to Ferrari – was 90 hp per liter, up from 80 hp per liter for the 5.5-liter engine from the 456. Another eight years before Ferrari made the V12 Similar power per liter as the DiV6 using the F133E engine in the 575M Maranello (2002). Proof that the engineers’ creativity was by no means a gimmick, but one that deserves recognition in the relentless pursuit of performance. It might be as daring as the DiV6.

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